The Mailman Research Center (MRC) at McLean Hospital is a critical component to our translational studies of the causes and treatments of neuropsychiatric disorders. The MRC Imaging Facility must replace our outmoded Leica confocal microscope with a state-of-the-art instrument. This will enhance our ability to perform co- localization studies of cellular and molecular mechanisms within neuronal subpopulations that regulate complex neural circuits involved in emotion and cognition. Ongoing work in the MRC focuses on corticolimbic circuits believed to be dysfunctional in patients with major psychoses, mood and anxiety disorders, post-traumatic stress, development disorders and neurodegenerative diseases. This proposal describes the need for a Leica TCS SP5 confocal microscope. This instrument will provide MRC investigators with a broad array of imaging capabilities. We currently have JEOL 1200EX electron microscope and a Leica confocal microscope; both were purchased with funds awarded through two separate NIH Shared Instrumentation Grants. In 1985, when the EM was procured, we established a Users Committee and this has served as a governing body for the Imaging Facility since that time. If this application is successful, our Users Committee will coordinate the use and maintenance of the new confocal microscope. Since 1985, a financial plan for the support of our Imaging Facility has been in place and will be amended to cover the new instrumentation. Historically, McLean Hospital has provided additional support for this facility and will continue to do so. The procurement of the proposed equipment will ensure that the MRC at McLean Hospital will be able to maintain a cutting edge research program for the study of neuropsychiatric disorders. PUBLIC HEALTH RELEVANCE: McLean Hospital has a multidisciplinary research program directed at the study of psychosis, mood and anxiety disorders, post-traumatic stress, development disorders and neurodegenerative diseases. The productivity of this program is dependent upon the availability of state-of-the-art imaging technology for visualizing neuronal circuitry both structurally and functionally. This proposal describes our need for a new sophisticated confocal imaging instrument that will allow us to function at the cutting edge of psychiatric neuroscience where it will be possible to develop innovative new approaches to the treatment of neuropsychiatric disorders.